1. Field of the Invention
The invention relates to the field of ophthalmic medicine, and in particular to the augmentation of filtation surgery for the treatment of glaucoma by photodynamic therapy.
2. Description of the Prior Art
Glaucoma is a disease of the eye wherein the ocular pressure within the eye increases to a magnitude that optic nerve damage occurs and permanent blindness results. One of the prior art methods of treating glaucoma is to make an incision through the sclera of the eye, a trabecutomy, to provide a means by which the ocular fluid may escape and the pressure may be relieved. To prevent scar tissue from closing the incision and thereby rendering the overlying conjunctiva more permeable to the expressed intraoccular liquid, an antimytotic agent is delivered to the conjunctiva to interfere with or block subsequent formation of fibrotic tissue.
The difficulty with this prior art technique has been that the delivery of the chemotherapeutic agent has been difficult to control both spatially and in terms of tissue uptake or dosage. The application of too high a dosage may result in destruction or serious damage to tissue well beyond simply interfering with the normal healing processes. Furthermore, even in cases where application and dosage of chemotherapeutic agents can be acceptably controlled, the long term effects of the use of such agents are only now becoming known and may be unacceptable. For example, it may be possible that by the use of such agents in a trabeculectomy may years later make the eye more susceptible to invasion by diseases than would normally be expected, or the eye pressure may go down too low causing a loss in vision.
Therefore, what is needed is some type of apparatus and method whereby diseases such as glaucoma may be surgically treated in a more controlled manner and with the minimization of possible side-effects.